<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux.git/arch/x86/kernel/cpu/mcheck, branch v3.11</title>
<subtitle>Linux kernel source tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/'/>
<entry>
<title>x86/mce: Fix mce regression from recent cleanup</title>
<updated>2013-07-29T18:23:27+00:00</updated>
<author>
<name>Tony Luck</name>
<email>tony.luck@intel.com</email>
</author>
<published>2013-07-24T17:09:43+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=1a7f0e3c4fff449f6dd08787beb98a8e57d8cdc7'/>
<id>1a7f0e3c4fff449f6dd08787beb98a8e57d8cdc7</id>
<content type='text'>
In commit 33d7885b594e169256daef652e8d3527b2298e75
   x86/mce: Update MCE severity condition check

We simplified the rules to recognise each classification of recoverable
machine check combining the instruction and data fetch rules into a
single entry based on clarifications in the June 2013 SDM that all
recoverable events would be reported on the unaffected processor with
MCG_STATUS.EIPV=0 and MCG_STATUS.RIPV=1.  Unfortunately the simplified
rule has a couple of bugs.  Fix them here.

Acked-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
In commit 33d7885b594e169256daef652e8d3527b2298e75
   x86/mce: Update MCE severity condition check

We simplified the rules to recognise each classification of recoverable
machine check combining the instruction and data fetch rules into a
single entry based on clarifications in the June 2013 SDM that all
recoverable events would be reported on the unaffected processor with
MCG_STATUS.EIPV=0 and MCG_STATUS.RIPV=1.  Unfortunately the simplified
rule has a couple of bugs.  Fix them here.

Acked-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86: delete __cpuinit usage from all x86 files</title>
<updated>2013-07-14T23:36:56+00:00</updated>
<author>
<name>Paul Gortmaker</name>
<email>paul.gortmaker@windriver.com</email>
</author>
<published>2013-06-18T22:23:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=148f9bb87745ed45f7a11b2cbd3bc0f017d5d257'/>
<id>148f9bb87745ed45f7a11b2cbd3bc0f017d5d257</id>
<content type='text'>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: x86@kernel.org
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Acked-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The __cpuinit type of throwaway sections might have made sense
some time ago when RAM was more constrained, but now the savings
do not offset the cost and complications.  For example, the fix in
commit 5e427ec2d0 ("x86: Fix bit corruption at CPU resume time")
is a good example of the nasty type of bugs that can be created
with improper use of the various __init prefixes.

After a discussion on LKML[1] it was decided that cpuinit should go
the way of devinit and be phased out.  Once all the users are gone,
we can then finally remove the macros themselves from linux/init.h.

Note that some harmless section mismatch warnings may result, since
notify_cpu_starting() and cpu_up() are arch independent (kernel/cpu.c)
are flagged as __cpuinit  -- so if we remove the __cpuinit from
arch specific callers, we will also get section mismatch warnings.
As an intermediate step, we intend to turn the linux/init.h cpuinit
content into no-ops as early as possible, since that will get rid
of these warnings.  In any case, they are temporary and harmless.

This removes all the arch/x86 uses of the __cpuinit macros from
all C files.  x86 only had the one __CPUINIT used in assembly files,
and it wasn't paired off with a .previous or a __FINIT, so we can
delete it directly w/o any corresponding additional change there.

[1] https://lkml.org/lkml/2013/5/20/589

Cc: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Cc: Ingo Molnar &lt;mingo@redhat.com&gt;
Cc: "H. Peter Anvin" &lt;hpa@zytor.com&gt;
Cc: x86@kernel.org
Acked-by: Ingo Molnar &lt;mingo@kernel.org&gt;
Acked-by: Thomas Gleixner &lt;tglx@linutronix.de&gt;
Acked-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Signed-off-by: Paul Gortmaker &lt;paul.gortmaker@windriver.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux</title>
<updated>2013-07-11T19:26:08+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-07-11T19:26:08+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=8cbd0eefcaf8cc32ded2bf229f0fc379b2ad69f2'/>
<id>8cbd0eefcaf8cc32ded2bf229f0fc379b2ad69f2</id>
<content type='text'>
Pull thermal management updates from Zhang Rui:
 "There are not too many changes this time, except two new platform
  thermal drivers, ti-soc-thermal driver and x86_pkg_temp_thermal
  driver, and a couple of small fixes.

  Highlights:

   - move the ti-soc-thermal driver out of the staging tree to the
     thermal tree.

   - introduce the x86_pkg_temp_thermal driver.  This driver registers
     CPU digital temperature package level sensor as a thermal zone.

   - small fixes/cleanups including removing redundant use of
     platform_set_drvdata() and of_match_ptr for all platform thermal
     drivers"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux: (34 commits)
  thermal: cpu_cooling: fix stub function
  thermal: ti-soc-thermal: use standard GPIO DT bindings
  thermal: MAINTAINERS: Add git tree path for SoC specific updates
  thermal: fix x86_pkg_temp_thermal.c build and Kconfig
  Thermal: Documentation for x86 package temperature thermal driver
  Thermal: CPU Package temperature thermal
  thermal: consider emul_temperature while computing trend
  thermal: ti-soc-thermal: add DT example for DRA752 chip
  thermal: ti-soc-thermal: add dra752 chip to device table
  thermal: ti-soc-thermal: add thermal data for DRA752 chips
  thermal: ti-soc-thermal: remove usage of IS_ERR_OR_NULL
  thermal: ti-soc-thermal: freeze FSM while computing trend
  thermal: ti-soc-thermal: remove external heat while extrapolating hotspot
  thermal: ti-soc-thermal: update DT reference for OMAP5430
  x86, mcheck, therm_throt: Process package thresholds
  thermal: cpu_cooling: fix 'descend' check in get_property()
  Thermal: spear: Remove redundant use of of_match_ptr
  Thermal: kirkwood: Remove redundant use of of_match_ptr
  Thermal: dove: Remove redundant use of of_match_ptr
  Thermal: armada: Remove redundant use of of_match_ptr
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull thermal management updates from Zhang Rui:
 "There are not too many changes this time, except two new platform
  thermal drivers, ti-soc-thermal driver and x86_pkg_temp_thermal
  driver, and a couple of small fixes.

  Highlights:

   - move the ti-soc-thermal driver out of the staging tree to the
     thermal tree.

   - introduce the x86_pkg_temp_thermal driver.  This driver registers
     CPU digital temperature package level sensor as a thermal zone.

   - small fixes/cleanups including removing redundant use of
     platform_set_drvdata() and of_match_ptr for all platform thermal
     drivers"

* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/rzhang/linux: (34 commits)
  thermal: cpu_cooling: fix stub function
  thermal: ti-soc-thermal: use standard GPIO DT bindings
  thermal: MAINTAINERS: Add git tree path for SoC specific updates
  thermal: fix x86_pkg_temp_thermal.c build and Kconfig
  Thermal: Documentation for x86 package temperature thermal driver
  Thermal: CPU Package temperature thermal
  thermal: consider emul_temperature while computing trend
  thermal: ti-soc-thermal: add DT example for DRA752 chip
  thermal: ti-soc-thermal: add dra752 chip to device table
  thermal: ti-soc-thermal: add thermal data for DRA752 chips
  thermal: ti-soc-thermal: remove usage of IS_ERR_OR_NULL
  thermal: ti-soc-thermal: freeze FSM while computing trend
  thermal: ti-soc-thermal: remove external heat while extrapolating hotspot
  thermal: ti-soc-thermal: update DT reference for OMAP5430
  x86, mcheck, therm_throt: Process package thresholds
  thermal: cpu_cooling: fix 'descend' check in get_property()
  Thermal: spear: Remove redundant use of of_match_ptr
  Thermal: kirkwood: Remove redundant use of of_match_ptr
  Thermal: dove: Remove redundant use of of_match_ptr
  Thermal: armada: Remove redundant use of of_match_ptr
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'please-pull-mce-therm' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux</title>
<updated>2013-07-03T18:16:09+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-07-03T18:16:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=a9f4a7005fb1a0f6142cbb689e734621c61574d5'/>
<id>a9f4a7005fb1a0f6142cbb689e734621c61574d5</id>
<content type='text'>
Pull thermal power-limit update from Tony Luck:
 "Thermal limit warnings are too scary and cause unnecessary concern"

* tag 'please-pull-mce-therm' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  x86 thermal: Disable power limit notification interrupt by default
  x86 thermal: Delete power-limit-notification console messages
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull thermal power-limit update from Tony Luck:
 "Thermal limit warnings are too scary and cause unnecessary concern"

* tag 'please-pull-mce-therm' of git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux:
  x86 thermal: Disable power limit notification interrupt by default
  x86 thermal: Delete power-limit-notification console messages
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge branch 'x86-tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip</title>
<updated>2013-07-02T23:31:49+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2013-07-02T23:31:49+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=96a3d998fb92c28b9862297fcf93a24d8a0eac1d'/>
<id>96a3d998fb92c28b9862297fcf93a24d8a0eac1d</id>
<content type='text'>
Pull x86 tracing updates from Ingo Molnar:
 "This tree adds IRQ vector tracepoints that are named after the handler
  and which output the vector #, based on a zero-overhead approach that
  relies on changing the IDT entries, by Seiji Aguchi.

  The new tracepoints look like this:

   # perf list | grep -i irq_vector
    irq_vectors:local_timer_entry                      [Tracepoint event]
    irq_vectors:local_timer_exit                       [Tracepoint event]
    irq_vectors:reschedule_entry                       [Tracepoint event]
    irq_vectors:reschedule_exit                        [Tracepoint event]
    irq_vectors:spurious_apic_entry                    [Tracepoint event]
    irq_vectors:spurious_apic_exit                     [Tracepoint event]
    irq_vectors:error_apic_entry                       [Tracepoint event]
    irq_vectors:error_apic_exit                        [Tracepoint event]
   [...]"

* 'x86-tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tracing: Add config option checking to the definitions of mce handlers
  trace,x86: Do not call local_irq_save() in load_current_idt()
  trace,x86: Move creation of irq tracepoints from apic.c to irq.c
  x86, trace: Add irq vector tracepoints
  x86: Rename variables for debugging
  x86, trace: Introduce entering/exiting_irq()
  tracing: Add DEFINE_EVENT_FN() macro
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull x86 tracing updates from Ingo Molnar:
 "This tree adds IRQ vector tracepoints that are named after the handler
  and which output the vector #, based on a zero-overhead approach that
  relies on changing the IDT entries, by Seiji Aguchi.

  The new tracepoints look like this:

   # perf list | grep -i irq_vector
    irq_vectors:local_timer_entry                      [Tracepoint event]
    irq_vectors:local_timer_exit                       [Tracepoint event]
    irq_vectors:reschedule_entry                       [Tracepoint event]
    irq_vectors:reschedule_exit                        [Tracepoint event]
    irq_vectors:spurious_apic_entry                    [Tracepoint event]
    irq_vectors:spurious_apic_exit                     [Tracepoint event]
    irq_vectors:error_apic_entry                       [Tracepoint event]
    irq_vectors:error_apic_exit                        [Tracepoint event]
   [...]"

* 'x86-tracing-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/tracing: Add config option checking to the definitions of mce handlers
  trace,x86: Do not call local_irq_save() in load_current_idt()
  trace,x86: Move creation of irq tracepoints from apic.c to irq.c
  x86, trace: Add irq vector tracepoints
  x86: Rename variables for debugging
  x86, trace: Introduce entering/exiting_irq()
  tracing: Add DEFINE_EVENT_FN() macro
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'please-pull-mce' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras into x86/ras</title>
<updated>2013-06-28T09:09:26+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2013-06-28T09:09:26+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=fb476cffd5e345434c03f3c0e82a7e8d87f98ab0'/>
<id>fb476cffd5e345434c03f3c0e82a7e8d87f98ab0</id>
<content type='text'>
Pull MCE cleanup from Tony Luck:

 "Changes to simplify the SDM means that we can also simplify
  the code for SRAR (software recoverable action required) errors."

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull MCE cleanup from Tony Luck:

 "Changes to simplify the SDM means that we can also simplify
  the code for SRAR (software recoverable action required) errors."

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86/mce: Update MCE severity condition check</title>
<updated>2013-06-27T20:45:52+00:00</updated>
<author>
<name>Chen Gong</name>
<email>gong.chen@linux.intel.com</email>
</author>
<published>2013-06-20T09:16:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=33d7885b594e169256daef652e8d3527b2298e75'/>
<id>33d7885b594e169256daef652e8d3527b2298e75</id>
<content type='text'>
Update some SRAR severity conditions check to make it clearer,
according to latest Intel SDM Vol 3(June 2013), table 15-20.

Signed-off-by: Chen Gong &lt;gong.chen@linux.intel.com&gt;
Acked-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Update some SRAR severity conditions check to make it clearer,
according to latest Intel SDM Vol 3(June 2013), table 15-20.

Signed-off-by: Chen Gong &lt;gong.chen@linux.intel.com&gt;
Acked-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>Merge tag 'please-pull-mce-bitmap-comment' of git://git.kernel.org/pub/scm/linux/kernel/git/ras/ras into x86/ras</title>
<updated>2013-06-26T08:53:45+00:00</updated>
<author>
<name>Ingo Molnar</name>
<email>mingo@kernel.org</email>
</author>
<published>2013-06-26T08:53:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=ca02c216742c9e6aa6c4dce31a0be417bc6685b3'/>
<id>ca02c216742c9e6aa6c4dce31a0be417bc6685b3</id>
<content type='text'>
Pull MCE updates from Tony Luck:

 "Better comments so we understand our existing machine check
  bank bitmaps - prelude to adding another bitmap soon."

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull MCE updates from Tony Luck:

 "Better comments so we understand our existing machine check
  bank bitmaps - prelude to adding another bitmap soon."

Signed-off-by: Ingo Molnar &lt;mingo@kernel.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>mce: acpi/apei: Add comments to clarify usage of the various bitfields in the MCA subsystem</title>
<updated>2013-06-25T20:53:27+00:00</updated>
<author>
<name>Naveen N. Rao</name>
<email>naveen.n.rao@linux.vnet.ibm.com</email>
</author>
<published>2013-06-25T18:28:59+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=0644414e62561f0ba1bea7c5ba6a94cc50dac3e3'/>
<id>0644414e62561f0ba1bea7c5ba6a94cc50dac3e3</id>
<content type='text'>
There is some confusion about the 'mce_poll_banks' and 'mce_banks_owned'
per-cpu bitmaps.  Provide comments so that we all know exactly what these
are used for, and why.

Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Acked-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
There is some confusion about the 'mce_poll_banks' and 'mce_banks_owned'
per-cpu bitmaps.  Provide comments so that we all know exactly what these
are used for, and why.

Signed-off-by: Naveen N. Rao &lt;naveen.n.rao@linux.vnet.ibm.com&gt;
Acked-by: Borislav Petkov &lt;bp@suse.de&gt;
Signed-off-by: Tony Luck &lt;tony.luck@intel.com&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>x86, trace: Add irq vector tracepoints</title>
<updated>2013-06-21T05:25:34+00:00</updated>
<author>
<name>Seiji Aguchi</name>
<email>seiji.aguchi@hds.com</email>
</author>
<published>2013-06-20T15:46:53+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux.git/commit/?id=cf910e83ae23692fdeefc7e506e504c4c468d38a'/>
<id>cf910e83ae23692fdeefc7e506e504c4c468d38a</id>
<content type='text'>
[Purpose of this patch]

As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.

http://www.spinics.net/lists/mm-commits/msg85707.html

&lt;snip&gt;
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled.  They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.

There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers.  Tracing such events gives
us the information about IRQ interaction with other system events.

The trace also tells where the system is spending its time.  We want to
know which cores are handling interrupts and how they are affecting other
processes in the system.  Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
&lt;snip&gt;

On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.

I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.

[Patch Description]

Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.

So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
   - local_timer_vector
   - reschedule_vector
   - call_function_vector
   - call_function_single_vector
   - irq_work_entry_vector
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
 - Create trace irq handlers with entering_irq()/exiting_irq().
 - Create a new IDT, trace_idt_table, at boot time by adding a logic to
   _set_gate(). It is just a copy of original idt table.
 - Register the new handlers for tracpoints to the new IDT by introducing
   macros to alloc_intr_gate() called at registering time of irq_vector handlers.
 - Add checking, whether irq vector tracing is on/off, into load_current_idt().
   This has to be done below debug checking for these reasons.
   - Switching to debug IDT may be kicked while tracing is enabled.
   - On the other hands, switching to trace IDT is kicked only when debugging
     is disabled.

In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.

Signed-off-by: Seiji Aguchi &lt;seiji.aguchi@hds.com&gt;
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
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[Purpose of this patch]

As Vaibhav explained in the thread below, tracepoints for irq vectors
are useful.

http://www.spinics.net/lists/mm-commits/msg85707.html

&lt;snip&gt;
The current interrupt traces from irq_handler_entry and irq_handler_exit
provide when an interrupt is handled.  They provide good data about when
the system has switched to kernel space and how it affects the currently
running processes.

There are some IRQ vectors which trigger the system into kernel space,
which are not handled in generic IRQ handlers.  Tracing such events gives
us the information about IRQ interaction with other system events.

The trace also tells where the system is spending its time.  We want to
know which cores are handling interrupts and how they are affecting other
processes in the system.  Also, the trace provides information about when
the cores are idle and which interrupts are changing that state.
&lt;snip&gt;

On the other hand, my usecase is tracing just local timer event and
getting a value of instruction pointer.

I suggested to add an argument local timer event to get instruction pointer before.
But there is another way to get it with external module like systemtap.
So, I don't need to add any argument to irq vector tracepoints now.

[Patch Description]

Vaibhav's patch shared a trace point ,irq_vector_entry/irq_vector_exit, in all events.
But there is an above use case to trace specific irq_vector rather than tracing all events.
In this case, we are concerned about overhead due to unwanted events.

So, add following tracepoints instead of introducing irq_vector_entry/exit.
so that we can enable them independently.
   - local_timer_vector
   - reschedule_vector
   - call_function_vector
   - call_function_single_vector
   - irq_work_entry_vector
   - error_apic_vector
   - thermal_apic_vector
   - threshold_apic_vector
   - spurious_apic_vector
   - x86_platform_ipi_vector

Also, introduce a logic switching IDT at enabling/disabling time so that a time penalty
makes a zero when tracepoints are disabled. Detailed explanations are as follows.
 - Create trace irq handlers with entering_irq()/exiting_irq().
 - Create a new IDT, trace_idt_table, at boot time by adding a logic to
   _set_gate(). It is just a copy of original idt table.
 - Register the new handlers for tracpoints to the new IDT by introducing
   macros to alloc_intr_gate() called at registering time of irq_vector handlers.
 - Add checking, whether irq vector tracing is on/off, into load_current_idt().
   This has to be done below debug checking for these reasons.
   - Switching to debug IDT may be kicked while tracing is enabled.
   - On the other hands, switching to trace IDT is kicked only when debugging
     is disabled.

In addition, the new IDT is created only when CONFIG_TRACING is enabled to avoid being
used for other purposes.

Signed-off-by: Seiji Aguchi &lt;seiji.aguchi@hds.com&gt;
Link: http://lkml.kernel.org/r/51C323ED.5050708@hds.com
Signed-off-by: H. Peter Anvin &lt;hpa@linux.intel.com&gt;
Cc: Steven Rostedt &lt;rostedt@goodmis.org&gt;
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